| 摘要 |
A control unit inquires through an IEEE 1394 serial bus in which power supply mode digital devices stored in a storage table of a memory are operating. If the response represents that the power supply mode is a power supply ON mode, the control unit allows the corresponding icons (61-1, 61-2) to be displayed normally; if the response represents that the mode is a connection stand-by mode, the control unit allows the corresponding icon (61-3) to be displayed in a screened display way; and if no response is received, the control unit allows the corresponding icons (61-4, 61-5) to be displayed in a reversed way. A connection detecting circuit (111) detects the bias voltage of the IEEEE1394 serial bus (101) and outputs its detection signal to a main control circuit (122). The main control circuit (122) controls a power supply circuit (117) so as to supply stand-by power to a stand-by power supply circuit (116) according to the input detection signal. The stand-by power supply circuit (116) supplies stand-by power to a physical connection circuit (112), a logical connection circuit (113), and a stand-by control circuit (121) according to an instruction of the main control circuit (122).
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